Electric-sign controller



Sept. 16, 1930." w STAFFORD 1,775,949

ELECTRIC 8 IGN CONTROLLER Filed Dec. 26, 1929 Fly. 1.

Patented Sept. 16, 1930 PATENT OFFICE WILFRED STAFFORD, OF HERNE HILL, LONDON, ENGLAND ELECTRIC-SIGN CONTROLLER Application filed December 26, 1929, Serial No. 416,585, and in Great Britain August 20, 1928.

This invention relates to means for control- I ling a plurality of electric circuits in a oer-- vices, or the like, may be operated automatically in sequence. The invention is particularly designed for automatically switching on a number of electric lamps in a desired sequence, switching ofi substantially simultaneously, switching on again, and so on. In such an application, to which the followin description, for convenience, has been con ed spelling electric signs can be worked in a simple manner, i. e. where electrically-illuminated letters can be successively switched on to spell out a word, name or phrase.

The invention further relates to that type of controlling means of the above class wherein a thermally-actuated switch (in which movement is brought about by the expansion and contraction of a bimetallic strip or equivalent thermal element under the influence of an electric heating element) carries a line of contacts which can be closed on to fixed points as the switch pivotally moves. The contacts control the lamp or other circuits, and one contact controls the make-and-break of the heating element. a The present invention is designed to pro vide a practical .form of such a type by ensuring that the maximum electric load in the control is not carried through any one 'pair of contacts, and certainly not through the make-and-break device of the thermal switch if. such closed position until the power I of such magnet or equivalent is overcome by 9 the potential energy accumulated in the thermal element due to the heating thereof, a quick and instantaneous break then being effected for all contacts practically simultaneously, when the element has been suflicient'ly heated to cause it to break away suddenly from the retaining magnet or equivalent.

The total electric load for the whole control is distributed to avoid any single pair of contacts carrying more than. the fraction required for the particular circuit, and thus, in conjunction with the quick simultaneous break, there is no possibility of dangerous and damaging sparking no matter how many lamps or other devices are employed.

In order that the said invention may be 66 more clearly understood, reference is to be had to the following description and accompanying drawings, wherein Figure 1 is an elevation of the automatic switch device, showing typical wiring for 7 nine lamps (wherein, for example, two are p on a common line.)

Figure? is a side sectional elevation of one of the pairs of contacts.

Referring to the drawings, the device illustrated (apart from the lamps 1 to 9) is adapted to be built to occupy avery small space and it can be mounted directly on the back of a sign casing containing the lamps,

or could be mounted separately in some remote position, if desired.

To facilitate a ready understanding of the drawings, the lamps, leads and terminals of common circuits are designated by similar numerals 1 to 9 inclusive. On an insulating baseboard a is pivoted at b, at one end, a movable switch member 0 in the form of a lever lying more or less horizontally across the baseboard. This carries a plurality of springy contacts d slidable in an insulating block 6 and having lower contacting extremities which can be pressed up against the coiled springy electrical connecting wires f. The reaction of the springs f is against the rigid baseboard a so as to avoid compression strains from the springs coming upon the pivoted switch member when the latter is closing. The movable lever c and its contacts (1 co-act with a complemental set of contacts g adjustably carried in a fixed switch member 72. mounted on the base a underneath the contacts 01. The contacts 9 re spectively form pairs with the upper complemental contacts (1 is the circuits 1 to 7. The last lamp (or lamps 8 and 9, in this example, which are commonly Wired for simultaneous control) are preferably under the control of contacts 2' and j at the remote end of the lever c, and contact 2' need not necessarily be springy. The screw designated is is an adjustable limiting stop for the upward movement of the lever a.

The arm a and its contacts on cooling of the thermal element normally falls on to the contacts 9 into circuits closed position,

' and the contacts 9 and the springs of the contacts 03 are so adjusted that the circuits 1 to 9 are established in definite sequence progressively from the contact 1 nearest the pilot I) travelling outwardly to 8 and 9. It will be obvious that either (a) the contacts could be wired difl'erently; or adjusted difierently to produce various sequences of illumination at the lamps other than progressive from end -to end.

To provide a retaining power for the circuits closed position, and to provide for a quick break under thermal influence (as described later), a soft iron block Z is fixed to the lever 0 and arranged to be attracted by a permanent magnet m, so that the thermal unit on heating will gradually store up potential energy until sufiicient is available to overcome suddenly the magnetic retaining power, and thus instantaneously jerk up the lever 0, giving a. substantially simultaneous break for all contacts. This quick break is assisted by mounting the magnet movably if desired. For instance, an advantageous arrangement is to fix the magnet m to a lever n pivoted at 0, said lever n at the other side of the pivot being linked to the top switch lever 0 by a link p. Thus magnet m and block Z break apart, each moving at the same time in opposite directions.

It will be clear that, according to the adj ustment of the contacts, a sequential break of the circuits could be provided.

The thermally expansible member is conveniently a bi-metallic strip 9 of a springy nature, fixed at r to the baseboard a above the member a, and having its free end linked at s to the said member 0. This strip q is heated electrically by a circuit controlled by contacts on the arm 0, preferably in series, as illustrated, with the last lamps 8 and 9.

The electrical leads from the main are in? dicated by the letters t and u, and it will be seen that the total electric load is distributed independently through the contacts and circuits 19 to avoid excessive sparking at any point.

Operation..The sign is first switched on by a main control tumbler or other switch inthe leads to t or u. Normally, thermal element 9 cold, the arm a is down and held by gravity and magnet m. All lamps are illuminated, the element 9 is gradually warming via the current through contacts 8 9, and after a pre-arranged period (dependent upon strength of magnet, expansib-ility of element 9 and so forth), the element g, which has been tending to expand, and, owing to its arcuate shape, to bend and straighten out, builds up sufficient energy to overcome the retaining powers of ,arm a and springs up, breaking all circuits, suddenly and practically simultaneously, including that of the heating element around strip g itself. Thereupon, the strip gradually cools and assumes its normal position, arm 0 lowering under its original influences, and contacts again being made gradually in sequence 1 to 9. After contact is established at 8, 9, the strip g is again heated and the cycle repeated.

The circuits 19 may control single or groups of lamps. Alternatively, or addition ally, other electrically-energized devices may be operated in a desired sequence by this automatic control. Obviously, ofcourse, any suitable plurality of contacts or-lamps other than 8 or 9 could be employed.

I claim p 1. An automatic thermal switching device for controlling a circuit to a plurality of electric devices, making circuit in a pro-arranged sequence and breaking in substantially simultaneous manner, comprising a base, a movable switch member pivoted thereon, a fixed switch member secured to, the base, a plurality of contacts carried by the pivoted switch member, a complemental set of contacts carried by the fixed switch member, a thermal expansible and bendable strip secured at one end to the movable switch element, an electric heating element wound around said thermal strip and included in I each lamp or group of lamps, and a complemental set of contacts along the fixed switch member forming pairs with their movable complements and fed from the main, a bimetal thermally .expansible and bendable strip secured to one end of the base and linked at the other end to the movable'switch element, an electric heating element wound around said thermal strip in series with the WILFRED STAFFORD. 

